Tests of Non-Causality Under Markov Assumptions for Qualitative Panel Data

For many years, social scientists have been interested in obtaining testable definitions of causality [C. W. Granger (1969)]. Recent works include those of G. Chamberlain (1982) and J. P. Florens and M. Mouchart (1982). The present paper first clarifies the results of these latter papers by considering a unifying definition of non-causality. Then, log-likelihood ratio (LR) tests for non-causality are derived for qualitative panel data under the minimal assumption that one series is Markov. LR tests for the Markov property are also obtained. Both test statistics have closed forms. These tests thus provide a readily applicable procedure for testing non-causality on qualitative panel data. Finally, the tests are applied to French Business Survey data in order to test the hypothesis that price changes from period to period are strictly exogenous to disequilibria appearing within periods

Inner Space Preserving Generative Pose Machine

Image-based generative methods, such as generative adversarial networks (GANs) have already been able to generate realistic images with much context control, specially when they are conditioned. However, most successful frameworks share a common procedure which performs an image-to-image translation with pose of figures in the image untouched. When the objective is reposing a figure in an image while preserving the rest of the image, the state-of-the-art mainly assumes a single rigid body with simple background and limited pose shift, which can hardly be extended to the images under normal settings. In this paper, we introduce an image "inner space" preserving model that assigns an interpretable low-dimensional pose descriptor (LDPD) to an articulated figure in the image. Figure reposing is then generated by passing the LDPD and the original image through multi-stage augmented hourglass networks in a conditional GAN structure, called inner space preserving generative pose machine (ISP-GPM). We evaluated ISP-GPM on reposing human figures, which are highly articulated with versatile variations. Test of a state-of-the-art pose estimator on our reposed dataset gave an accuracy over 80% on PCK0.5 metric. The results also elucidated that our ISP-GPM is able to preserve the background with high accuracy while reasonably recovering the area blocked by the figure to be reposed.Comment: http://www.northeastern.edu/ostadabbas/2018/07/23/inner-space-preserving-generative-pose-machine

Primate modularity and evolution: first anatomical network analysis of primate head and neck musculoskeletal system

Network theory is increasingly being used to study morphological modularity and integration. Anatomical network analysis (AnNA) is a framework for quantitatively characterizing the topological organization of anatomical structures and providing an operational way to compare structural integration and modularity. Here we apply AnNA for the first time to study the macroevolution of the musculoskeletal system of the head and neck in primates and their closest living relatives, paying special attention to the evolution of structures associated with facial and vocal communication. We show that well-defined left and right facial modules are plesiomorphic for primates, while anthropoids consistently have asymmetrical facial modules that include structures of both sides, a change likely related to the ability to display more complex, asymmetrical facial expressions. However, no clear trends in network organization were found regarding the evolution of structures related to speech. Remarkably, the increase in the number of head and neck muscles – and thus of musculoskeletal structures – in human evolution led to a decrease in network density and complexity in humans

Technologies des énergies renouvelables : fiche de synthèse 05

La région Languedoc-Roussillon bénéficie d'un des meilleurs gisements d'énergies renouvelables (EnR) de France, en particulier, en ce qui concerne l'énergie éolienne et l'énergie solaire. Elle est la seule région française qui développe des recherches relatives au solaire concentré et possède des installations de grande taille dans ce domaine. Un des trois pôles de compétitivité français relatifs aux EnR est basé en région (DERBI à Perpignan). Des technologies relatives aux EnR sont actuellement disponibles et matures (chaleur moyenne et basse température, photovoltaïque [PV], éolien) et devraient être développées très activement. Les points de vigilance concernent: l'acceptation des parcs éoliens, la concurrence sur l'utilisation de l'eau dans le cas du développement des agrocarburants. Les propositions d'actions sont: utiliser le pôle de compétitivité DERBI pour favoriser le développement des activités technologiques et économiques dans le domaine des EnR, promouvoir encore plus les EnR et les économies d'énergie dans l'habitat (pas seulement de l'eau chaude sanitaire), en particulier l'habitat à faible consommation et la climatisation solaire, renforcer la position unique de la région dans le domaine de la RDT sur le solaire concentré, encourager les recherches relatives au PV innovant, au stockage (électrochimique et thermique) à la production de combustibles alternatifs (hydrogène) et la gestion intelligente de l'énergie. (Résumé d'auteur

THE COST STRUCTURE OF MICROFINANCE INSTITUTIONS IN EASTERN EUROPE AND CENTRAL ASIA

Microfinance institutions are important, particularly in developing countries, because they expand the frontier of financial intermediation by providing loans to those traditionally excluded from formal financial markets. This paper presents the first systematic statistical examination of the performance of MFIs operating in Eastern Europe and Central Asia. A cost function is estimated for MFIs in the region from 1999-2004. First, the presence of subsidies is found to be associated with higher MFI costs. When output is measured as the number of loans made, we find that MFIs become more efficient over time and that MFIs involved in the provision of group loans and loans to women have lower costs. However, when output is measured as volume of loans rather than their number, this last finding is reversed. This may be due to the fact that such loans are smaller in size; thus for a given volume more loans must be made.http://deepblue.lib.umich.edu/bitstream/2027.42/40195/3/wp809.pd

Effect of Ce and Sb on Primary Graphite Growth in Cast Irons

It is well-known that if certain trace elements are present in cast iron melts the morphology of the graphite precipitates can be altered. In order to understand the effect of doping elements on primary growth of graphite, pure Fe–Sb alloys were prepared by induction melting. They were then placed in graphite crucibles and heated to a temperature above the Fe–C eutectic so that the charge became saturated in carbon and melted. To obtain Fe–Ce alloys, metallic Ce was added at the bottom of a graphite crucible and covered with iron, and then heated as for the Fe–Sb charge. In both cases, the melt was then cooled and held slightly above the eutectic temperature so that primary graphite crystals, which had nucleated on the crucible walls and then detached from it, could grow freely in the melt. The influence of the added elements on graphite growth was revealed by the change in the shape and distribution of the crystals compared to those obtained in similar experiments carried out with pure Fe. The experiments were made in air and vacuum so as to point out possible interactions between the elements present in the melt and oxygen

Microstructural Characterization of Graphite Spheroids in Ductile Iron

The present work brings new insights by transmission electron microscopy allowing disregarding or supporting some of the models proposed for spheroidal growth of graphite in cast irons. Nodules consist of sectors made of graphite plates elongated along a hai direction and stack on each other with their c axis aligned with the radial direction. These plates are the elementary units for spheroidal growth and a calculation supports the idea that new units continuously nucleate at the ledge between sectors

Incentivizing High Quality Crowdwork

We study the causal effects of financial incentives on the quality of crowdwork. We focus on performance-based payments (PBPs), bonus payments awarded to workers for producing high quality work. We design and run randomized behavioral experiments on the popular crowdsourcing platform Amazon Mechanical Turk with the goal of understanding when, where, and why PBPs help, identifying properties of the payment, payment structure, and the task itself that make them most effective. We provide examples of tasks for which PBPs do improve quality. For such tasks, the effectiveness of PBPs is not too sensitive to the threshold for quality required to receive the bonus, while the magnitude of the bonus must be large enough to make the reward salient. We also present examples of tasks for which PBPs do not improve quality. Our results suggest that for PBPs to improve quality, the task must be effort-responsive: the task must allow workers to produce higher quality work by exerting more effort. We also give a simple method to determine if a task is effort-responsive a priori. Furthermore, our experiments suggest that all payments on Mechanical Turk are, to some degree, implicitly performance-based in that workers believe their work may be rejected if their performance is sufficiently poor. Finally, we propose a new model of worker behavior that extends the standard principal-agent model from economics to include a worker's subjective beliefs about his likelihood of being paid, and show that the predictions of this model are in line with our experimental findings. This model may be useful as a foundation for theoretical studies of incentives in crowdsourcing markets.Comment: This is a preprint of an Article accepted for publication in WWW \c{opyright} 2015 International World Wide Web Conference Committe

Viable tax constitutions

Taxation is only sustainable if the general public complies with it. This observation is uncontroversial with tax practitioners but has been ignored by the public finance tradition, which has interpreted tax constitutions as binding contracts by which the power to tax is irretrievably conferred by individuals to government, which can then levy any tax it chooses. However, in the absence of an outside party enforcing contracts between members of a group, no arrangement within groups can be considered to be a binding contract, and therefore the power of tax must be sanctioned by individuals on an ongoing basis. In this paper we offer, for the first time, a theoretical analysis of this fundamental compliance problem associated with taxation, obtaining predictions that in some cases point to a re-interptretation of the theoretical constructions of the public finance tradition while in others call them into question